Data in a distributed database system is stored across a multitude of physically and/or logically distinct nodes. For example, data in a distributed database system may be stored on different computers. Alternately or additionally, data in a distributed database system may be managed by separate processes. As such, in order to fulfill a query in a distributed database system, multiple nodes are often required to perform one or more specific operations on the data stored at and/or managed by each individual node. For instance, a scheduler node can derive an execution plan setting forth the operations required to fulfill the query as well as the interdependencies amongst the operations. Meanwhile, one or more worker nodes can perform the operations assigned to each worker node in the execution plan. The nodes (e.g., scheduler and worker nodes) that are involved in the execution of the query can exchange messages (e.g., control messages) in order to coordinate the execution of the query pursuant to the execution plan.